Many forms of balers are well known today. The most commonly used field baler of today forms a rectangular bale by picking up crop material by means of a crop pickup, transferring the crop material laterally by means of packer fingers to the forward end of a bale chamber, and then compressing the crop material into a bale by means of a plunger which conventionally operates in the range of 50 to 100 strokes per minute. The bales are then tied off into lengths which generally vary from three to four feet in length. Most of these bales have a 14 or 16 inch by 18 inch cross section and can be manually handled after baling. Hay baled by machines of this type are of good quality and suitable for long term storage.
During the past 20 years efforts have been made to develop other bale packages which are more suitable for machine handling. One approach is the large rectangular baler of the types shown in U.S. Pat. Nos. 3,552,109 and 4,118,918. To produce large rectangular bales by the conventional baler system, such as used for the smaller 16 by 18 inch bales, a machine must have a relative heavy structure, and a power train capable of transmitting high torques due to the very high peak loads which occur for a small portion of each cycle when the plunger is completing its stroke. In addition, problems have been encountered when tying off such bales.
The manner in which both the small and large rectangular bales have been tied off is essentially the same. Thus, one end of a twine is held by a knotter, the twine then passing across the leading face of the bale and being held by a needle disposed on the side of the bale chamber opposite from the knotter. When the desired length of the bale has been attained, the tying mechanism is initiated at which point the needle carries an intermediate portion of the twine through the bale chamber to the knotter where the twine is cut and tied about the bale. Customarily, the bale is provided with two or three knotters, although for larger balers more knotters may be employed. While this mechanism performs in a generally satisfactory manner on the smaller balers, difficulties have been encountered with larger balers.
In addition to the various commercial types of balers referred to above, other prior art forms of balers have been suggested. One such type is shown in the Molitorisz U.S. Pat. No. 4,175,487. This form of baler utilizes cooperating rollers which are moved back and forth across the inlet end of the bale chamber. A baler of this general type may be used for both forming small rectangular bales and large rectangular bales. In addition, it has been found that balers of this type have relatively low power requirements. However, the use of a conventional twine needle unnecessarily complicates the design of such a baler, and in addition increases the power requirements of the baler when bringing the twine into the knotter for tying.